Update Available Notification Block for React

No. The run is three setTimeouts that you start by pressing Update now (about a second apart, cleared on Cancel and when the block leaves the page); the Progress value is the step it has reached, and the "Downloading 48 MB" line is typed. Restart to finish only says it is done. In your app, drive the Progress from your updater's real events and call its restart from the button.

So the primary is always in the same place: Update now, then Downloading (quiet and refused while it runs), then Restart to finish, then Up to date (quiet again). The label changes inside a fixed minimum width so the card never reflows. The quiet states keep focus and say why they wait in the status line, since a disabled button would drop focus.

It opens a labelled Remind me choice in the card's info slot, in the same space as the download line, so nothing moves. Choosing writes "We'll remind you on Thu 15 Oct, 09:00 (demo)" from AS_OF plus the number of days in REMINDERS, or "after the next release" when it isn't a date, and returns focus to Later. Nothing is scheduled in this demo; in your app, save the moment and show the card again then. While a download runs, the same button reads Cancel, and when the update is done it reads Replay.

The card is a named section with a heading, the highlights are a list, every control is a real button or a labelled select, and one polite status line says what each press did. The card is not timed and not modal: it never takes focus, and the drawn app under it is hidden from assistive technology. The quiet buttons use the page's own text colour at full opacity so they stay readable.

The card spans the stage minus a margin and the stage is taller; the title may wrap onto a second line, which its space already holds, and the two buttons stay on one row at the card's foot.